Cygnus gas field

The Cygnus gas field is a natural gas reservoir and gas production facilities in the UK sector of the southern North Sea. It is about 150 km of east of the Lincolnshire coast and started gas production in 2016.

Cygnus gas field
Country	United Kingdom
Region	North Sea
Location/blocks	44/11a, 44/12a
Offshore/onshore	Offshore
Coordinates	54°34’14”N 02°17’28”E
Operator	Neptune E&P UK Ltd
Owner	Spirit Energy (61.25 %) and Neptune Energy (38.75 %)
Field history
Discovery	1988
Start of production	December 2016
Production
Recoverable gas	760×10^^9 cu ft (22×10^^9 m^3)
Producing formations	Permian sandstones, Carboniferous

The field

The Cygnus field extends over UK offshore Blocks 44/11a and 44/12a. The field was discovered in 1988 by Marathon Oil.^[1] The reservoirs are Permian Leman sandstone and Carboniferous sandstone formations and have recoverable reserves of 760 billion cubic feet.^[1]

In 2019 the Cygnus gas field was jointly owned by Spirit Energy (61.25 %) and Neptune Energy (38.75 %), Neptune E&P UK Ltd operates the infrastructure.^[1]

Development

Production from the field has been developed in stages. In the first stage gas was produced by wells on the Cygnus Alpha platform and then routed by pipeline to the Bacton Gas Terminal via the Esmond Transmission System.^[1] The next stage entailed development of the north west part of the field produced from the Cygnus Bravo platform which was routed 7 km to the Cygnus Alpha installation.^[1]

Details of the Cygnus field infrastructure are as shown.^[1][2][3][4]

Cygnus installations

Platform name	Cygnus A WHP	Cygnus A PU	Cygnus A QU	Cygnus B
Block	44/11a	44/11a	44/11a	44/12a
Installation type	Fixed Steel platform	Fixed Steel platform	Fixed Steel platform	Fixed Steel platform
Coordinates	54°36’36”N  02°22’29”E	54°34’14”N  02°17’28”E	54°34’12”N  02°17’23”E	54°35’59”N  02°11’46”E
Function	Wellheads	Processing and utilities	Accommodation and utilities	Wellheads
Crew	66			Unattended
First gas	December 2016			August 2017
Water depth, metres	22.5	22	21.7	22
Design	AMEC
Jacket fabrication	BiFab Methil
Jacket weight, tonnes	1,858	3,146	1,958	2,194
Topside fabrication	Heerema Hartlepool		BiFab	Heerema Hartlepool
Topsides dimensions, metres	23 x 23 x 10
Topsides weight, tonnes	1,474	3,911	2,960	2,753
No. of legs	4	8	4
No. of well slots	10	–	–	10
No. of Wells		–	–
Production to	Cygnus APU across bridge	Bacton via Esmond system	–	Cygnus A PU
Production capacity		9.1×10^^6 m^3 (320×10^^6 cu ft) per day	–
Pipeline length and diameter	–	50 km, 610 mm	–	7.28 km, 324 mm (12.75 in)
Pipeline Number	–	PL3088	–	PL3086

Production

Cygnus gas has a minimum Wobbe Index of 46.6 to 46.8 MJ/m³. This is below the minimum specification for entry into the National Transmission System (47.2 MJ/m³). Cygnus gas en route to Bacton, commingles within the ETS pipeline with gas from Trent and Tors fields. The mixed gas arrives at Bacton with a minimum Wobbe index of 46.5 to 46.7 MJ/m³. If there is a reduction of gas flow from the other fields that deliver gas to Bacton then the output of Cygnus is constrained. To maintain Cygnus flow a temporary reduction of Wobbe Index from 47.2 MJ/m³ to 46.5 MJ/m³ at the NTS entry point at Bacton terminal was agreed in 2020.^[5]

See also

• Bacton gas terminal
• List of oil and gas fields of the North Sea
• Esmond, Forbes and Gordon gas fields
• Tyne, Trent and Tors gas fields

References

1. "Cygnus gas field development". www.nsenergybusiness.com. from the original on 2021-03-02. Retrieved 22 December 2021.
2. "Cygnus". www.spirit-energy.com. from the original on 2018-08-14. Retrieved 22 December 2021.
3. "Inventory of Offshore Installations". odims.ospar.org. from the original on 2021-11-25. Retrieved 22 December 2021.
4. "OGA interactive Maps". ogauthority.maps.arcgis.com. from the original on 2019-01-26. Retrieved 22 December 2021.
5. "Amendment to Network Entry Provision at Perenco Bacton Terminal" (PDF). www.gasgovernance.co.uk. (PDF) from the original on 2021-12-23. Retrieved 23 December 2020.